The objective of this research project is to increase and extend the usefulness of optical techniques, especially circular dichroism (CD) in the study of protein structure and function. Various model systems will be studied experimentally and theoretically. The vacuum ultraviolet spectra of polypeptides in various conformations will be studied. The CD of twisted beta-structures will be characterized theoretically and model parallel and antiparallel beta-structures of known width will be synthesized and characterized. The CD of aromatic homopolypeptides such as poly-L-tyrosine and of cyclic peptides with aromatic side-chains will be treated theoretically. Experimental and theoretical CD studies of heme proteins will be carried out. The origin of heme CD bands in cytochrome c will be examined and the assignment and nature of charge-transfer transitions will be probed. Hemoglobins from various species, mutant human hemoglobins and modified hemoglobins will be studied by CD to characterize the heme pocket and intersubunit interactions. Heme-heme interactions in hemoglobin and cytochrome oxidase will be characterized more fully. The binding of triphenylmethyl dyes to dehydrogenases will be studied. The active sites of lactic dehydrogenase isozymes, of malic DH, and glyceraldehyde-3-phosphate DH will be probed. The use of dyes such as Cibacron Blue F3G-A and Congo Red as probes of the dinucleotide fold in dehydrogenases and kinases will be explored. Chromium complexes of ATP will be resolved into their isomers and used to determine the stereochemistry of metal-nucleotide complex binding sites in kinases. The interaction of actinomycin D, ethidium Br and other intercalating dyes with DNA will be studied with CD.